The Eleven Cities Tour is an ice skating tour over 200 km on natural ice of canals. The delegates start in the morning and have to finish before 12 midnight. I have skated the tour in 1985,1986 and 1987.
Tour number 16 in 2007?
Prediction of the year of the next eleven cities tour; Most tours are held in years with a decreasing branche of he sun spot activity graph. So that 2006,2007 or 2008 looks most reasonable years for a next tour.

Sunspot activity related to Eleven Cities Tours ( actual activity).
More about the sun!.

From 1950 the ice skating tour was only organized in years with the lowest sunspot activity. Mid 70th it was also cold enough to organize the skating tour. The organization committee, however, remembers still very well the injuries during the heavy tour in 1963, so that they did not take the opportunity. Up to 1950 there were many exceptions. One of the reasons is that only a few hundred delegates (in later tours it were several thousands, up to 17000) were skating the traject. Another reason could be the lower peak values of sunspots in the first part of 1900. The peaks have became higher from 1940. Perhaps a simple explanation why the earth is heating up somewhat. And why there were so many Eleven Cities Tours around the 1940's.
P.S. Also the stock market looks to be influenced by the sunspot cycle. So some patient is required to make profit.

UPDATE 13 January 2009 ; From end of December until January 11 there was a rather strong freezing period. In the South of the Netherlands temperatures of -18 degrees Celcius have been measured during several nights. However, there was no Eleven Cities Tour because the high pressure region was not located at the South of Sweden, but more above Scotland. This causes that it was not so cold in the North of the Netherlands. But anyway, it has already been shown that the colder winters are separated by 11 years periods. Question is; why was the high pressure area not located at the desired position. Could it be possible that the large amount of wind turbines in that region are influensing the system??

UPDATE 8 January 2010 ; About 1.5 weeks before Christmas it starts freezing. At Saturday 19 December 2009 I scated already on natural ice at a small canal. Up to the end of December the temperature was not very low and for Dutch meanings there was a lot of snow. In January 2010, however, the temperature decreases up to -17 degrees. In this period low temperatures are measured in the North of the Netherlands, also. A long term cold period has been predicted, so that an Eleven Cities Tour should become possible. However, unfortunately a lot of snow has been dropped, just short after the canals were frozen. The ice was at that moment too weak to remove the snow. The snow layer slows down the growing of the thickness of the ice floor, and also the quality of the ice becomes bad. So, even when it is freezing enough in the coming period it is still doubtfull if the big tour will be possible.
But anyway this winter has shown again the possible relation between sun spot activity and strong winters in the Netherlands. It is shown, also, again that strong winters comes in pairs on two. Fortunately there is good change for a next strong winter (2011), because the sunspots counts are not increasing as usual.
Question is: why is there so much snow. It seems that the snow border has been moved to the West. A possible explanation for this is the large amount of wind turbines. I believe that when a significant amount of energy is extracted from the wind the climat in that region will be influenced. This is comparabel with co2 production.

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